Chuck



Dec. 7, 1948. AT 2355,66?

CHUCK Filed Nov. 15, 1945 :s shaets S 'heettl I Patented Dec. 7, 1948 UNITE-D STATES DIFFICFE onUoKw. a a John Eaton, Cheltenham, Enland, assignor' "to StanleyCharlesIcke,Solihull, England istsisaionsmaw 15,1945,

i In Great :Britain November :23, 1-944 12' Claims. (cilia-" 118) This invention has reference to work holding and similar rotary chucks -for lathes and like machines.

The principal object of the present invention is to enable the jaws of a chuck to be locked automatically when taken to their work gripping positions so that there is no necessity to apply a manual, pneumatic, hydraulic or other load or pressure on the jaw actuating lmeans orwotherwise make special provision .fonpreventin g. the. jaws moving under the aotionof centrifugal force,

a chuck in which the flaws are-adapted to be operated rapidly and easily to and fromtheir work gripping positions. l i I Still another object otthe invention is to provide a chuck whiohdoesnot necessitate the .pro-

vision of a separate lkey or other tool "for taking the jaws to their work gripping positions.

Still anotherobject of the inventionis to enable the jaws of a chunk to be adjusted relatively to one another, in a rapid and easy mann rsto enable work pieces of varying dimensions, within limits, to be gripped in the same chucks A further object of the invention is to .provide simple'androbust pneumatically controlledmeans for operating the jaws of the chuck, the said operating means :being capahle of being wreadily incorporated in any lathe -or like machine and being suitable for use for operating chucks of various sizes. l i I i These and other objectswand advantages of the invention will become apparent to those skilled in the art upon reference to thenaccompanying specification, claims and drawings In order that the invention may be more readily understood and carried into practice, reference will now be made to drawings wherein:

the accomp:shying H i Figure 1 is asectionalelevation showingwhe chuck jaws in their work gripping. positions.

Figure is a similar view to Figure 1 except that it shows the jaws expanded m d)" to receive a work piece. v.

FigureB is a similar view to Figured of an alternative or modified ;form of {hue/lg, showing thejaws in a work-grippingpositions V Eigure '4 is aisectionalclevation to 7 Sean 628,695

a 2 u're l but showing the jaws positioned for gripping workljof largerr'dimensions than when positioned as jshow'nin Figure 3. j liFigure 5 is .a sectional elevation of mechanism for actuating thedraw bar, and

Figure 6 is a sectional elevation at right angles to Figure 5. 1 t

"The chuck shoWni'nEigures 1 and 2 comprises apa'ird f permanent "jafw's l which are slidably hQused-injradial channels 2 formed in the face clan annular insert 3fixed infthe mouth of a housing A, the housing being carried upon the lathe spindle 5. The said permanent jaws are adapted to carry any desired temporary work holding or nose jaws t is common practice. fEach permanent jaw l is 'formed with a slot I in its rear face, thati's, the face adjacent the housing. The said slotis engaged by a rollerl ikejhead B on a jaw-levers; the said lever is pivotedflupon a pin ljO carried by thei nser't .3, at a short distance "from the said roller-like head. The other end of the jaw-lever 9 is journalled by-a pin 1 l to one end of a complementary over-centre lever I2, {the other end of which is hinged by a pin is between cheeks I'd formed on 'the end ofa resilient arm lt of a plunger It. The levers 59, 12, are thus coupled togglewise between the plunger l6 and the com lementary permanent jaws l. The jaw-lever 9 is formed longitudinally, witha channel or slot ll-l, which is adaptedto receive the journal led end of the overvoentr-e lever 12 so as to enable the toggle tofibe col-lapsed substantially completely. .The

said hinged end of .the over-centre lever I2 is formed with a flattenetlfedge or heel l8.

'The plunger IGisfslidably housed in asleevelikehushl'fl fitted within the bore of the lathe spindle, is connected co-axially to one end of a drawebar *Zil which extends axially of the said bore and is arrangedso that the resilient arms 15 projectinto the centre of the tog gle housingl v.

plunger isals o formed with a-blind axial andftappedhole or pocket [2! with which an externally and internally threaded tube22 engages. .f-llhe tube .22 extends into the toggle housing beyond the ends of theiresilientlever-carrying arms l5,and is formed with a hexagona'l head 22*? and a peri-nheralfshoulder 22 The head is accessible by a tool, such as a box spanner, inserted between the chuck jaws and 6 to permit of the tube being rotated in the blind hole or pocket 2 l and tlf'iereby {being adjusted longitudinally relatively totheres'ilient arms and toggles. A screw 23, screwedfintolfthe interior the tube T2,, is

formed with a slotted head capable of being engaged by a screw driver inserted between the chuck jaws, so that it may be rotated in, and displaced longitudinally relatively to, the said tube. Thus, the inner end of the screw 23 may be taken into contact with, and may thrust against, the bottom of the blind hole or pocket 2! for locking the sleeve 22 in position.

A wedge 24 is carried on the tube 22 with its deeper end in abutment with the peripheral collar 22 This wedge is formed with four inclined fiat faces 24, the said faces on two opposed sides of the wedge seat against the inner surfaces 15*- on the plunger arms I5. The said wedgecontacting faces l5 diverge at the same angle as the wedge faces so that any longitudinal adjustment of the tube 22 causes the wedge to be located at a greater or lesser distance in between the arm ends so as to vary the distance to which the latter are forced apart. The said two inclined wedge faces are also contacted by the flattened edges or heels I8 of vthe over centre levers l2, when the jaws are in .itheirwork-gripping positions. Thus, by increasing or decreasing the distance between the said arm ends, the distances between the hinge pins I l and between the work holding faces of the jaws 6, when in their work gripping. positions; are increased or decreased.

The arrangement is preferably such that the two pairs of toggle levers are arranged in a common plane on opposite sides of the resilientarms. Thus by actuating the draw-bar to move the armed plunger and wedge assembly towards the jaw-carrying end of the housing, the toggles are collapsed. The journalled connections H between the levers therefore move towards the centre of the housing, causing the jaw levers to turn on their pivot pins in the direction which takes their roller-like heads 8, and, consequently the jaws, radially of the housing towards the periphery of the latter, thereby opening the jaws.

Conversely, by actuating the draw-bar in the reverse direction, the plunger and wedge assembly is drawn away from the jaws. The toggles are thus expanded and the jaw levers swing in the direction which move the jaws together to hold a work piece. Simultaneously, the overcentre levers move towards their dead-centre positions wherein they are at right angles to the resilient arms, and as they pass over the said positions, away from the jaws, their flat faces or heels I8 contactthe wedge faces thereby preventing any further movement of the toggles, jaws, draw bar, and plunger.

Since the over-centre levers are now past their dead-centre positions, then, when the chuck is in use and is rotating at speed, the action of centrifugal force on the jaws, which tends to separate the latter, tends to expand the toggles. This expansion, however, is prevented by the contact between the lever heels and the wedge faces and, therefore, the jaws are locked.

To enable the jaws to grip a work piece of larger cross-sectional dimensions, the sleeve 22 is unlocked after the jaws have been opened by withdrawing the screw 23 out of contact with the bottom of the plunger bore 2!, and the said sleeve is then rotated in the direction which permits the wedge to be withdrawn partially from between the resilient arms [5. The said arms, therefore, flex inwardly towards one another thereby moving the fulcra of the over-centre H levers inwardly of the housing and swinging the .jaw levers througha small angle, around the pins l0 in'the direction which increases the" distance between the expanded jaws. Consequently, when the draw bar is actuated to displace the jaws inwardly towards one another then, as the draw-bar and jaw movements strokes are constant or substantially constant, the distance between the work-gripping faces of the jaws, when they assume their work-gripping positions, will be increased by a corresponding amount.

In the chuck shown in Figures 3 and 4, such adjustment is effected automatically because, instead of having a rigid connection between the wedge 24 and plunger Hi, this connection is effected through a coil spring 25. This spring is carried upon one end of a rod 26 having an enlarged head 21 which forms one of the spring abutments. The head is slidable within a housing 28 provided in the plunger l5 and the end of the said housing forms the other spring abutment. The rod 26 extends between the flexible plunger arms I5 into the toggle housing 4 and carries the wedge 24 on its end located within the said housing; the wedge is keyed upon the rod in such manner that it can slide longitudinally thereon, but is normally retained by the spring 25 in abutment with a nut 29, screwed on to the rod 26, and theinclined flat faces or heels I8 of the over-center levers l2.

Consequently, when the draw-bar is actuated to move the toggles from their collapsed to their expanded positions, to cause the jaws to grip a work piece, the plunger l5, rod 26 and wedge 24 move as a unit untilthework gripping faces of the jaws impact the work piece. Whereupon, I any continued movement of the draw-bar sets up a relative movement between the plunger and rod, causing the heels of the flexible arms to 'slide down the wedge faces, and compressing the spring between its abutments; the overcentre toggle levers are taken past their deadcentre positions by the travel of the pins [3 away from the jaws. g

A pneumatically controlled mechanism, suitable for actuating the draw bar, is shown in Figures 5' and 6. r This mechanism is mounted on the rear end of the lathe head stock 30; it comprises a' link 3! journalled between the head stock, at a position below the lathe spindle 5, and the lower end of the lever 32 having a bifurcated upper end. Two superimposed trunnion blocks 33 and 34 are journalled between the arms of the said bifurcated end. The lower block 33 embraces a sleeve 35 carried on the rear end of the draw bar 20 whereas a pneumatic cylinder 36 is carried by the upper block 34 which block is provided with a bush 3! through which extends the rod 38 of a double-acting piston 39 housed within the cylinder, the said rod and piston being fixed to the head stock.

The lower trunnion block 33 is socketed on to the end of the draw bar sleeve 35 and is held in position by a collar 40 screwed on to the rear end of the draw bar and locked in position by a nut 4|.

In order that the head stock spindle 5 may carry as little weight as possible, the mass of the lever and trunnion blocks is balanced by a tension spring 42 connected between the link 31 and an anchorage 43carriedon the rear end of the head stock between the said link and the lathe spindle.

A compressed air pipe is connected between each of the inlets 44, 45,in the ends of the cylinder and a control valve (not shown) mounted in a position on the lathe where it is readily accessible to the operatoi'. by admitting comtary jaw and the other lever, which latter lever is hingedly connected to the said arm and is carried through a position of dead-centre into abutment with the wedge as the said complementary jaw assumes its work-gripping position.

7. A rotary chuck comprising a system of work gripping jaws slidable relatively to one another in a radial direction, an axially slidable draw bar disposed centrally of the jaw system, a plunger anchored by one end to the said draw bar and being formed at its other end with a system of resilient arms, equal in number to the jaws, a roddisposed between the said arms and having a resilient connection to the plunger, a wedge carried by the said rod and projecting between the said arms and a separate toggle link connecting each arm to a separate jaw and comprising two levers one of which is journalled between its ends and is hingedly connected to and between the complementary jaw and the other lever, which latter lever is hingedly connected to the said resilient arm and is carried through a dead centre position into abutment with the wedge as the .said complementary jaw reaches its work-gripping position.

8. A rotary chuck comprising a rotatable housing, work gripping jaws mountedin a-radially slidable manner on the said housing, a longitudinally. slidable plunger mounted co-axially of V the housing being connected to a draw bar at one end, and being formed-with a system of resilient arms, equal in number to the jaws, at the other end, a rod slidably housed within the plunger and being loaded by a spring tending to drive it towards the draw bar,.a wedge slidably mounted on the rodbetween the resilient arms, and a togglelink connecting each resilient arm to a separate jaw, each toggle link comprising two levers one of which is journalled within the housing andis hingedly connected to and between the complementary jaw and the other lever, the latter lever being hingedly connected to the said resilient arm and being adapted to abut the wedge when moved through a dead 9. A rotary chuck comprising a system of work gripping jaws slidable relatively to one another in a radial direction, an axially slidable draw bar disposed centrally of the jaw system, a plunger anchored at one end'to the said draw bar and having a chamber in the said anchored end and being formed at its other end with a system of resilient arms equal in number to the jaws, a rod slidably carried within the plunger and extending from the said chamber to between the resilient arms, the said rod having an enlarged head located within the chamber, a coil-spring compressed betweenthe said head and the chamber end remote from the draw bar, a wedge .carried by the rod between the resilient arms, a toggle link connecting each of the said arms .to a separate jaw and comprising a pair of levers one of which is journalled intermediate its ends and is hingedly connected to and between the complementary jaw and the other lever, said other. lever being hingedlyconnectedto the com-;

plementary resilient arm and being carried through a dead centre position into abutment with the wedge as "the complementary jaw is taken to its work gripping position by' the expansion of the toggle links when the plunger is displaced longitudinally away from the jaw system.

10. A' rotary chuck comprising a' system of work gripping jaws slidable relatively to one another in a radial direction, a. longitudinally slidable hollow plunger disposed centrally of the said jaw system and anchored to a draw bar at one end thereof, a separate toggle link coupling the other endof 'the said plunger to each jaw, each of the said links comprising two levers one of which is journalled intermediate its ends and is hingedly connected to and between the complementary jaw and the other leverwhich is plunger are swung about their fulcra by endwise movement of the said plunger in the direction which moves the jaws radially inwards, the said levers abut inclined faces of the stop after the toggle links have passed through positions of dead centre, to limit the angular movement of the levers and determine the work-gripping position of the jaws.

11. A rotary chuck comprising a rotatable housing, a system of work-gripping jaws mounted in a radially slidable manner on the said housing, a longitudinally slidable hollow plunger mounted co-axially of the housing and having one end coupled to a draw-bar, a separate toggle-link coupling the other end of the said plunger to each of the said jaws, each link comprising two levers one of which is journalled intermediate its ends and is hingedly connected to and between a complementary jaw and the other lever of which is hingedly connected to the plunger, and a wedgelike stop located within the housing centrally of the jaw and toggle-link system, the said stop being carried upon and being adjustable endwise ofa rod housed within and co-axially of the plunger and being loaded by a spring which urges the rod towards the draw bar, the said stop having an inclined face adjacent each lever connection to the plunger, the arrangement being such that endwise movement of the plunger in the direction which rocks the said levers to impart inward radial movement to the jaws, causes each lever, after the link of which it forms a part has passed through its position of dead centre, to abut an inclined stop face thereby limiting the angular movement of the lever and determining the work-gripping position of the complementary jaw, the said position being variable by endwise movement of the stop upon the plunger.

12. A rotary chuck comprising a rotatable howsing, work gripping jaws mounted in a radially slidable manner on the said housing, a longitudinally slidable hollow plunger mounted coaxially of the housing, the said plunger being anchored to a draw-bar at one end, a rod housed within and co-axially of the plunger, 2. spring loading the said rod and urging it towards the draw-bar, a cone-shaped stop assembled to the end of the rod remote from the draw-bar in a.

longitudinally displaced away fromthe housing ,1 to expand the toggle links and take the jaws to their work-gripping positions, the said work- 10 gripping positions being determined by the location of the said stop lengthwise of the rod. JOHN EATON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 915,173 1 Hanson Mar. 16, 1909 1,117,480 1 Church Nov. 17, 1914 1,813,705 Lewis July 7, 1931 

